1. Field of the Invention
This invention relates to a method of absorbing stray light in an integrated optical circuit and to an integrated optical circuit comprising light absorbing means for absorbing stray light.
2. Description of the Related Art
In the design of integrated optical circuits there is often a need to deal with light which is not guided by the components forming the circuit. This stray light, which can arise from many sources, such as fibre or laser couplers, scattering from waveguide couplers and bends or from scattering beam dumps, can have a severe impact on the performance of devices which employ these components. The stray light in the optical chip can enter devices on the chip, and output fibres and may severely limit the performance of these devices.
Conventional methods of dealing with this problem include physically arranging devices on an integrated optical chip such that stray light cannot enter sensitive parts of the chip and the use of isolation trenches to keep stray light away from certain parts of the chip.
The imitation of these approaches is that they do not remove the stray light from the integrated optical chip, but instead attempt to minimise the problem of having stray light within the chip.